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Monkeypox

Information for healthcare providers about monkeypox.
About Monkeypox

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Background

Monkeypox is a viral infection, caused by a virus of the Orthopoxvirus genus. The first monkeypox cases in Canada were reported on May 19, 2022 in Montreal. British Columbia’s first case was confirmed on June 6, 2022. Additional cases continue to be reported in B.C., Canada and numerous countries. 

Case count and epidemiological summary


There are two circulating clades of the monkeypox virus: clade I (formerly named the Congo Basin Clade) and clade II (formerly named the West African Clade). Genomic studies linked most of the cases from the outbreak 2022 cases in Europe and America to clade II lineage B.1.

Clade II was seen in previous years’ outbreaks in the USA, Israel and Singapore and the 2017-2018 Nigeria outbreak and is associated with less severe disease and lower case fatality.

Among the monkeypox cases, a high proportion is in people who self-identify as gay, bisexual and other men who have sex with men (gbMSM). Though the reported cases thus far have been primarily among gbMSM, it is important to note that anyone can become exposed and infected. 

Monkeypox is not known to be sexually transmitted, but it can occur through close direct contact. Anyone with close and prolonged contact with a case of monkeypox is at risk of having the infection. 

Stigmatizing any group will hinder appropriate infection prevention and control efforts, and will be detrimental to the identification and management of additional cases. The recent cases among gbMSM are likely due in part to shared social networks, as well as large events that may have facilitated transmission.

In B.C.,  vaccination is available to close contacts and those at the highest risk of infection.  Public health will follow up with individuals who may have been exposed to monkeypox or who are identified as cases. 

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Clinical Presentation

Incubation: 5 to 21 days, usually 7 to 14 days

Image credit: United Kingdom

Clinical presentation resembles smallpox but is less severe. Symptoms can vary depending on different factors, including exposure characteristics, age, presence of conditions that alter immune response, previous immunity for smallpox and viral strain. 
 
Monkeypox infection has two clinical phases: 

  1. A prodromal illness that lasts between 1 to 5 days characterized by fever, intense headache, lymphadenophathy, back pain, myalgia, fatigue. Other symptoms have been also described, such as sore throat, cough and less frequently, vomiting or diarrhea. In some cases, no prodromal symptoms were reported or these symptoms occurred after the beginning of the rash. 
  2. A skin rash that begins 1-5 days after fever. The rash evolves from macules, papules, vesicles then pustules, before crusting, which then scale off. Lesions are frequently painful and can be pruritic. Lesions of different clinical stages can be present at the same moment. 

The number of lesions and affected regions can vary. Lesions can be found on all parts of the body, including palmar and plantar areas. 

In the current outbreak, lesions frequently begin and affect the genital, anal and oral areas. Some cases developed proctitis (for ex. rectal pain, bloody stools, diarrhea). Facial lesions can potentially lead to ocular involvement, affecting the conjunctivae and cornea.

Symptoms last 2 to 4 weeks.

Children, pregnant women and some immunocompromised individuals are considered at higher risk for severe disease. Recent cases in Canada and western countries have been described as mild. Since May 2022, no deaths have been reported in western countries.

Long-term skin effects, such as prolonged ulcer healing and scarring, have been described in the literature. Complications can include secondary infections (for example, cellulitis), and less frequently pneumonia, sepsis, encephalitis and keratitis leading to vision loss. 

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Transmission

Period of communicability: during the symptomatic period, including the prodrome. Lesions are considered infectious until the scabs fall off and new skin can be seen.

Modes of transmission

Monkeypox doesn't generally spread easily between people. Most historical transmissions occurred through close contact with infected animals (bite, scratch or ingesting meat). The current global outbreak, however, is facilitated by human-to-human transmission.

Human-to-human transmission occurs via:

  • Direct contact with cutaneous or mucosal lesions;
  • Fomites, i.e. contaminated material such as linens or clothing;
  • Respiratory droplets from prolonged face-to-face contact. 

Monkeypox has been detected in many body sites, including semen. However, the significance of this finding on the potential for sexual transmission through semen is not yet known. Transmissions in the context of sexual activity are likely related to close contact as described above.

Monkeypox virus can cross the placental barrier. No case of vertical transmission has been reported in non-endemic countries. However, a case of fetal infection with pathological signs of monkeypox has been described from an endemic country, indicating the potential for vertical transmission.

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Diagnosis & Testing

Monkeypox diagnosis is available at the BCCDC PHL by a validated, in-house PCR (nucleic acid) test (detecting the presence of monkeypox virus DNA in patient samples).

Refer to the Monkeypox Testing Guidelines for Primary Care in British Columbia, last updated August 30, 2022:Monkeypox Testing Guidelines for Primary Care in British Columbia


Prevention

Suspected cases should be instructed to limit their contact until results are obtained and practice frequent hand and respiratory hygiene. Lesions should be covered whenever possible, and contaminated objects should be manipulated by the case only.

Infection Prevention & Control

Refer to the Provincial Infection Control Network's infection prevention and control guidance for monkeypox, last updated August 8, 2022:B.C.'s interim infection prevention and control guidance for monkeypox in health care settings

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Patient Transport

If a patient suspected or confirmed to have monkeypox requires transportation, the patient must be provided with a medical mask and lesions must be covered (e.g., patient gown, sheet or dry dressing). The receiving department/facility and transporting personnel should be informed of the need for airborne, droplet and contact precautions.

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Immunization

Health Canada maintains a limited stockpile of monkeypox vaccine (Imvamune®) that is made available to BCCDC for use in the event of monkeypox cases. The National Advisory Committee on Immunization published recommendations for the use of Imvamune in the context of monkeypox outbreaks. In BC, regional public health authorities will identify contacts or any other high-risk group who is eligible and can benefit from the vaccine.

You can find the following resources in the BC Immunization Manual, Part 4, under ‘Monkeypox vaccine”

The following document provides a summary of available resources to support healthcare providers with intradermal (ID) administration of Imvamune®:


Treatment

Most individuals with monkeypox have mild symptoms and do not require any specific interventions. Treatment for monkeypox remains supportive and targeted on symptoms (e.g. fever control, hydration support, treat secondary infections). There are no specific antiviral treatments that have proven to be effective in human cases of monkeypox. 

The antivirals cidofovir, brindofovir, and tecovirimat have all been examined in in-vitro and/or animal models. Of these, only tecovirimat may be considered in severe cases of human monkeypox on a case-by-case basis.

Guidance for the treatment of Monkeypox

Prescribers should refer to the Prescriber Information and Ordering Process document for practical information regarding ordering tecovirimat. Health-authority based hospital pharmacy departments may also be contacted for information and guidance.Prescriber information and ordering process


Treatment with oral tecovirimat (TPOXXTM) can be considered in consultation with a physician from the Monkeypox Advisory and Guidance in the following patients with confirmed monkeypox infection:

 

  • Individuals (adults and children irrespective of age or smallpox vaccine status) with severe disease defined as either:
    • Requiring hospitalization or hospital-level care for monkeypox (e.g., due to severe, extensive and widespread lesions*) OR
    • Requiring hospitalization or hospital-level care for complications directly related to monkeypox (e.g., encephalitis, sepsis, pneumonia), OR
    • Significantly interfering with normal physiological body function (e.g., oral food intake, hydration, pain that is difficult to control or severe pain with bowel movements or urination) 

*Note: Many patients will present with genital, anal and/or oral lesions, as well as conjunctivitis. The location of lesions itself is not an indication for treatment. Treatment decisions should be based on the severity of the presentation. 


OR

  • Individuals who may be at high-riskof developing severe disease due to severe immunocompromise such as:
    • human immunodeficiency virus with a CD4 count < 200 cells/mm3, or a diagnosis of acquired immune deficiency syndrome for adults or a diagnosis of HIV for children
    • current treatment for a hematological malignancy such as leukemia or lymphoma
    • bone marrow/HSCT transplantation in the past 2 years
    • generalized malignancy (e.g., solid tumor or metastatic cancer)
    • solid organ transplantation
    • therapy with severely immunosuppressing agents (e.g., alkylating agents, antimetabolites, radiation, tumor necrosis factor inhibitors, high-dose corticosteroids, treatment for graft-versus-host disease or receiving immunosuppressive therapy for an autoimmune disease with immunodeficiency as a clinical component)
  • Neonates and infants < 1-year-old
  • Children aged 1-17 years with immunocompromising conditions (e.g., HIV, cancer, currently taking immunosuppressive therapy)
  • Pregnant persons

#Clinical judgement must be used when offering tecovirimat to non-severely ill patients who have been vaccinated with the smallpox vaccine (Vaccinia; Imvamune). Such patients are less likely to develop severe disease; however, the impact of smallpox vaccination in high-risk individuals infected with the recent strain of monkeypox has not been well characterized. In addition, vaccine timing (recent vs. decades ago) and immune status (during illness and at the time of vaccination) may impact vaccine response and must be strongly considered.


The recommended tecovirimat dosing is 600mg PO BID for adults weighing 40-124kg and 600mg PO TID for adults weighing 125kg or more.


The recommended duration of initial treatment is 7 days, with reassessment for the possibility of continued therapy for a total of 14 days. Treatment may be stopped after 7 days in those who are not severely ill, who are improving clinically and/or at the clinician’s judgement. Treatment should be extended to 14 days in pregnant patients, those who remain hospitalized, those who are not experiencing improvement/experiencing progression, severely immunocompromised individuals exhibiting new lesions while on treatment, and/or at the clinician’s judgement.


Pediatric dosing is weight-based: 13 to < 25kg: 200mg PO BID; 25 to < 40kg: 400mg PO BID; 40kg and over: refer to adult dosing. Tecovirimat capsules may be opened, mixed with food, or dissolved in liquid and given via feeding tubes. An IV formulation may be applied for through the Special Access Programme for those who are unable to take PO medications or for neonates between 3-13kg.


The use of cidofovir for monkeypox is NOT RECOMMENDED. Studies of animals challenged with lethal doses of with smallpox and monkeypox treated with cidofovir showed it to be less effective than tecovirimat in preventing mortality. 

Cidofovir is also associated with severe renal impairment when given for other indications.


 

The use of brincidofovir for monkeypox is NOT RECOMMENDED. 

Brincidofovir is not currently available in Canada. Brincidofovir is also associated with severe liver impairment in case-series of patients infected with monkeypox and when used for other indications.

 

The use of Vaccinia Immunoglobulin (VIG) for the treatment of monkeypox is NOT RECOMMENDED. 

VIG has been evaluated for the treatment of first-generation smallpox vaccine-induced adverse effects, and for prevention of smallpox in those in whom first-generation live vaccination was not recommended. VIG has not been evaluated for the treatment of monkeypox in animals or humans.


 



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